Semiconductor device and method of forming an alignment structure in backside of a semiconductor die

ABSTRACT

A semiconductor device has a semiconductor die containing a base material having an active surface and a back surface opposite the active surface. A portion of the base material is removed by plasma etching to form an alignment recess in the base material. Alternatively, an alignment protrusion is formed over the base material. The alignment recess or alignment protrusion make a non-uniform surface. The semiconductor die is disposed over a substrate with a portion of the substrate, such as a die pad, positioned within the alignment recess. The die pad may be disposed partially or completely within the alignment recess of the base material. The base material may extend beyond the die pad, or the alignment recess or alignment protrusion may extend a length of the base material. A metal layer can be formed in the alignment recess of the base material.

CLAIM TO DOMESTIC PRIORITY

The present application claims the benefit of U.S. Provisional Application No. 62/219,666, filed Sep. 17, 2015, entitled “SEMICONDUCTOR PACKAGES AND METHODS” invented by Francis J. CARNEY and Michael J. SEDDON, and which is incorporated herein by reference and priority thereto for common subject matter is hereby claimed.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and, more particularly, to a semiconductor device and method of forming an alignment notch or alignment protrusion in backside of a semiconductor die.

BACKGROUND

Semiconductor devices are commonly found in modern electronic products. Semiconductor devices vary in the number and density of electrical components. Semiconductor devices perform a wide range of functions such as analog and digital signal processing, sensors, transmitting and receiving electromagnetic signals, controlling electronic devices, power management, and audio/video signal processing. Discrete semiconductor devices generally contain one type of electrical component, e.g., light emitting diode (LED), small signal transistor, resistor, capacitor, inductor, diodes, rectifiers, thyristors, and power metal-oxide-semiconductor field-effect transistor (MOSFET). Integrated semiconductor devices typically contain hundreds to millions of electrical components. Examples of integrated semiconductor devices include microcontrollers, application specific integrated circuits (ASIC), standard logic, amplifiers, clock management, memory, interface circuits, and other signal processing circuits.

A need exists in the semiconductor industry for smaller package size so that the end products, such as cell phones, computers, and watches, can be reduced in size and weight. Advanced micro packaging and multichip packaging require precise die alignment tolerances. The die placement accuracy is dependent on variation in die size due to wafer saw, placement accuracy during pick and place operations, movement during reflow, and shifting or sliding off of a die pedestal within micro packaging. The alignment tolerance adds to the overall package dimensions and spacing limitations.

Common micro packaging relies on semiconductor die which are only partially placed on a planar surface of a die pad in order to meet the customer footprint requirements, i.e., the semiconductor die overhangs the die pad. FIG. 1a shows semiconductor die 50 partially placed on a planar surface of die pad 52 with a portion of the planar back surface 53 of the semiconductor die overhanging the die pad. Semiconductor die 50 is bonded to die pad 52 with an adhesive and active surface 54 is coupled to wire bond pad 56 with bond wire 58. Die pad 52 and wire bond pad 56 are integral components of a leadframe. An encapsulant 60 covers semiconductor die 50, wire bond pad 56, and bond wire 58.

Given the overhang of the planar back surface 53 of semiconductor die 50 with respect to the planar surface of die pad 52, semiconductor die 50 is susceptible to tilting, rotation, slipping off, or other undesired movement on die pad 52 during the manufacturing process. The planar back surface 53 of semiconductor die 50 may detach or otherwise shift in position with respect to die pad 52 by improper alignment, or by adhesive failure and tension of bond wire 58, as shown in FIG. 1b . Holding semiconductor die 50 to exact alignment tolerances is difficult and can lead to bond wire sweep, bond wire disconnect, or shorting of the bond wires. Since die pad 52 must be kept small in order to meet the customer footprint requirements, the die size is limited because of the relatively small die overhang that can be used before semiconductor die 50 becomes susceptible to slipping, tilting, rotation, or detachment from the die pad. The movement of large semiconductor die 50 with respect to small die pad 52 may constitute a manufacturing defect and reduce production yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a-1b illustrate a common mounting arrangement between a larger semiconductor die and smaller die pad;

FIGS. 2a-2c illustrate a semiconductor wafer with a plurality of semiconductor die separated by a saw street;

FIGS. 3a-3e illustrate a process of forming an alignment notch in a back surface of the semiconductor die;

FIG. 4 illustrates a semiconductor package with the semiconductor die mounted to a die pad within the backside alignment notch;

FIG. 5 illustrates another semiconductor package with the semiconductor die mounted to a die pad partially within the backside alignment notch;

FIG. 6 illustrates another semiconductor package with the semiconductor die mounted to a die pad partially within the backside alignment notch;

FIGS. 7a-7g illustrate another process of forming an alignment notch with backside metal;

FIG. 8 illustrates another semiconductor package with the semiconductor die mounted to a die pad within the backside metal alignment notch;

FIG. 9 illustrates another semiconductor package with the semiconductor die mounted to a die pad partially within the backside metal alignment notch;

FIGS. 10a-10c illustrate semiconductor die with elongated alignment notches mated to protrusions formed over a substrate;

FIGS. 11a-11c illustrate semiconductor die with cross-shaped alignment notches mated to cross-shaped protrusions formed over a substrate;

FIGS. 12a-12c illustrate semiconductor die with elongated alignment protrusions mated to recesses formed in a substrate;

FIGS. 13a-13c illustrate semiconductor die with cross-shaped alignment protrusions mated to cross-shaped recesses formed in a substrate;

FIGS. 14a-14b illustrate semiconductor die with alignment recesses or protrusions mated to corresponding structures formed in a PCB; and

FIGS. 15a-15c illustrate a semiconductor die with alignment protrusions inserted into mating openings formed through a substrate.

DETAILED DESCRIPTION OF THE DRAWINGS

The following describes one or more embodiments with reference to the figures, in which like numerals represent the same or similar elements. While the figures are described in terms of the best mode for achieving certain objectives, the description is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure. The term “semiconductor die” as used herein refers to both the singular and plural form of the words, and accordingly, can refer to both a single semiconductor device and multiple semiconductor devices.

Semiconductor devices are generally manufactured using two complex manufacturing processes: front-end manufacturing and back-end manufacturing. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each die on the wafer may contain active and passive electrical components and optical devices, which are electrically connected to form functional electrical circuits. Active electrical components, such as transistors and diodes, have the ability to control the flow of electrical current. Passive electrical components, such as capacitors, inductors, and resistors, create a relationship between voltage and current necessary to perform electrical circuit functions. The optical device detects and records an image by converting the variable attenuation of light waves or electromagnetic radiation into electric signals.

Back-end manufacturing refers to cutting or singulating the finished wafer into the individual semiconductor die and packaging the semiconductor die for structural support, electrical interconnect, and environmental isolation. The wafer is singulated using plasma etching, laser cutting tool, or saw blade along non-functional regions of the wafer called saw streets or scribes. After singulation, the individual semiconductor die are mounted to a package substrate that includes pins or contact pads for interconnection with other system components. Contact pads formed over the semiconductor die are then connected to contact pads within the package. The electrical connections can be made with conductive layers, bumps, stud bumps, conductive paste, or wirebonds. An encapsulant or other molding material is deposited over the package to provide physical support and electrical isolation. The finished package is then inserted into an electrical system and the functionality of the semiconductor device is made available to the other system components.

FIG. 2a shows semiconductor wafer 100 with a base substrate material 102, such as silicon, germanium, aluminum phosphide, aluminum arsenide, gallium arsenide, gallium nitride, indium phosphide, silicon carbide, or other bulk semiconductor material for structural support. A plurality of semiconductor die 104 is formed on wafer 100 separated by a non-active, inter-die wafer area or saw street 106, as described above. Saw street 106 provides cutting areas to singulate semiconductor wafer 100 into individual semiconductor die 104. In one embodiment, semiconductor wafer 100 has a width or diameter of 100-450 millimeters (mm) and thickness of 50-100 micrometers (μm) or 15-250 μm.

FIG. 2b shows a cross-sectional view of a portion of semiconductor wafer 100. Each semiconductor die 104 has a back or non-active surface 108 and an active surface or region 110 containing analog or digital circuits implemented as active devices, passive devices, conductive layers, and dielectric layers formed within the die and electrically interconnected according to the electrical design and function of the die. For example, the circuit may include one or more transistors, diodes, and other circuit elements formed within active surface or region 110 to implement analog circuits or digital circuits, such as digital signal processor (DSP), microcontrollers, ASIC, standard logic, amplifiers, clock management, memory, interface circuits, and other signal processing circuit. Semiconductor die 104 may also contain integrated passive devices (IPDs), such as inductors, capacitors, and resistors, for RF signal processing. Active surface 110 may contain an image sensor area implemented as semiconductor charge-coupled devices (CCD) and active pixel sensors in complementary metal-oxide-semiconductor (CMOS) or N-type metal-oxide-semiconductor (NMOS) technologies. Alternatively, semiconductor die 104 can be an optical lens, detector, vertical cavity surface emitting laser (VCSEL), waveguide, stacked die, electromagnetic (EM) filter, or multi-chip module.

An electrically conductive layer 112 is formed over active surface 110 using PVD, CVD, electrolytic plating, electroless plating process, or other suitable metal deposition process. Conductive layer 112 includes one or more layers of aluminum (Al), copper (Cu), tin (Sn), nickel (Ni), gold (Au), silver (Ag), titanium (Ti), titanium tungsten (TiW), or other suitable electrically conductive material. Conductive layer 112 operates as contact pads electrically connected to the circuits on active surface 110. Conductive layer 112 can be formed as contact pads disposed side-by-side along an edge of semiconductor die 104, as shown in FIG. 2b . Alternatively, conductive layer 112 can be formed as contact pads that are offset in multiple rows such that a first row of contact pads is disposed a first distance from the edge of the die, and a second row of contact pads alternating with the first row is disposed a second distance from the edge of the die.

Semiconductor wafer 100 undergoes electrical testing and inspection as part of a quality control process. Manual visual inspection and automated optical systems are used to perform inspections on semiconductor wafer 100. Software can be used in the automated optical analysis of semiconductor wafer 100. Visual inspection methods may employ equipment such as a scanning electron microscope, high-intensity or ultra-violet light, or metallurgical microscope. Semiconductor wafer 100 is inspected for structural characteristics including warpage, thickness variation, surface particulates, irregularities, cracks, delamination, and discoloration.

The active and passive components within semiconductor die 104 undergo testing at the wafer level for electrical performance and circuit function. Each semiconductor die 104 is tested for functionality and electrical parameters, as shown in FIG. 2c , using a test probe head 116 including a plurality of probes or test leads 118, or other testing device. Probes 118 are used to make electrical contact with nodes or conductive layer 112 on each semiconductor die 104 and provide electrical stimuli to contact pads 112. Semiconductor die 104 responds to the electrical stimuli, which is measured by computer test system 119 and compared to an expected response to test functionality of the semiconductor die. The electrical tests may include circuit functionality, lead integrity, resistivity, continuity, reliability, junction depth, ESD, RF performance, drive current, threshold current, leakage current, and operational parameters specific to the component type. The inspection and electrical testing of semiconductor wafer 100 enables semiconductor die 104 that pass to be designated as known good die (KGD) for use in a semiconductor package.

FIGS. 3a-3e illustrate a process of forming an alignment notch in back surface 108 of semiconductor die 104. In FIG. 3a , a portion of back surface 108 is removed by grinder 120 in a backgrinding operation. The backgrinding operation reduces a thickness of base substrate material 102 to surface 122 of the base substrate material. In one embodiment, semiconductor wafer 100 has a post-grinding thickness of 100 μm.

In FIG. 3b , semiconductor wafer 100 is inverted and a masking layer 126 is disposed over surface 122 of base substrate material 102. Masking layer 126 can be implemented as a photoresist layer or oxide layer with openings 128 extending to surface 122.

In FIG. 3c , surface 122 is plasma etched through openings 128 in masking layer 126 to form alignment notches or keyed recesses 130 in base substrate material 102 while in wafer form of FIG. 2a . Alternatively, alignment notches or keyed recesses 130 in base substrate material 102 can be formed by laser direct ablation (LDA) or other wet or dry chemical etching process.

In FIG. 3d , masking layer 126 is removed. Semiconductor die 104 are shown with alignment notches or keyed recesses 130 having side surfaces 132 and back surface 134 in base substrate material 102. Alignment notches 130 make a non-uniform thickness or surface of base substrate material 102.

In FIG. 3e , semiconductor wafer 100 is disposed over film frame or backing tape 136 with surface 122 and alignment notches 130 oriented toward the film frame. Semiconductor wafer 100 is singulated through saw street 106 into individual semiconductor die 104 using plasma etching. Plasma etching has advantages of removing base substrate 102 to form precision surfaces, while retaining the structure and integrity of the base substrate material. Alternatively, semiconductor wafer 100 is singulated through saw street 106 using a saw blade or laser cutting tool 137 into individual semiconductor die 104. The individual semiconductor die 104 can be inspected and electrically tested for identification of KGD post singulation.

FIG. 4 illustrates a semiconductor package 138 containing semiconductor die 104 with alignment notch or keyed recess 130 formed in base substrate material 102 disposed over die pad 140. In particular, surfaces 132 and 134 of notch 130 provide alignment for mounting semiconductor die 104 to die pad 140. In one embodiment, die pad 140 has thickness of 30-40 μm and semiconductor die 104 has thickness of 50-100 μm. Semiconductor die 104 is larger than die pad 140 resulting in a significant extension of base substrate material 102 beyond the die pad. Die pad 140 is completely contained with alignment notch 130 to securely hold semiconductor die 104 to the die pad. The smaller die pad 140 allows for smaller semiconductor package dimensions and package footprint to meet industry demands. Even with the smaller die pad 140, semiconductor die 104 is robust against laterally slippage, tilting, shifting, or detachment with respect to the die pad because the surfaces of the die pad are disposed within notch 130. Semiconductor die 104 can be significantly larger than die pad 140 with the use of alignment notch 130, while avoiding the manufacturing slippage, tilt, rotation, or detachment defect noted in FIGS. 1a -1 b.

Bond wire 144 is connected between conductive layer or contact pad 112 on active surface 110 and wire bond pad 146. Die pad 140 and wire bond pad 146 represent a portion of a leadframe, substrate, interposer, or semiconductor die. An optional insulating layer 148 is formed over surface 122 of semiconductor die 104 using PVD, CVD, printing, spin coating, spray coating, sintering or thermal oxidation. The insulating layer 148 contains one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, or other material having similar insulating and structural properties. Insulating layer 148 is exposed from semiconductor package 138. An encapsulant or molding compound 150 is deposited over semiconductor die 104, bond wire 144, and wire bond pad 146 using a compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, or other suitable applicator. Encapsulant 150 can be polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 150 is non-conductive, provides physical support, and environmentally protects the semiconductor device from external elements and contaminants.

FIG. 5 illustrates a semiconductor package 160, similar to FIG. 4, containing semiconductor die 104 with a shallow alignment notch or keyed recess 130 formed in base substrate material 102 disposed over die pad 162. In particular, surfaces 132 and 134 of notch 130 provide alignment for mounting semiconductor die 104 to die pad 162. Semiconductor die 104 is larger than die pad 162 resulting in a significant extension or overhang of base substrate material 102 beyond the die pad. Die pad 162 is partially contained with alignment notch 130 to securely hold semiconductor die 104 to the die pad. A portion of die pad 162 extends vertically outside alignment notch 130. The smaller die pad 162 allows for smaller semiconductor package dimensions and package footprint to meet industry demands. Even with the smaller die pad 162, semiconductor die 104 is robust against laterally slippage, tilting, shifting, or detachment with respect to the die pad because the surfaces of the die pad are disposed at least partially within notch 130. Semiconductor die 104 can be significantly larger than die pad 162 with the use of alignment notch 130, while avoiding the manufacturing slippage, tilt, rotation, or detachment defect noted in FIGS. 1a -1 b.

Bond wire 164 is connected between conductive layer or contact pad 112 on active surface 110 and wire bond pad 166. Die pad 162 and wire bond pad 166 represent a portion of a leadframe, substrate, interposer, or semiconductor die. An encapsulant or molding compound 170 is deposited over semiconductor die 104, bond wire 164, and wire bond pad 166 using a compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, or other suitable applicator. Encapsulant 170 can be polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 170 is non-conductive, provides physical support, and environmentally protects the semiconductor device from external elements and contaminants.

FIG. 6 illustrates a semiconductor package 180, similar to FIG. 5, containing semiconductor die 104 with a shallow alignment notch or keyed recess 130 formed in base substrate material 102 disposed over die pad 182. In particular, surfaces 132 and 134 of notch 130 provide alignment for mounting semiconductor die 104 to die pad 182. Semiconductor die 104 is larger than die pad 182 resulting in a significant extension or overhang of base substrate material 102 beyond the die pad. Die pad 182 is partially contained with alignment notch 130 to securely hold semiconductor die 104 to the die pad. A portion of die pad 182 extends vertically outside alignment notch 130. The smaller die pad 182 allows for smaller semiconductor package dimensions and package footprint to meet industry demands. The alignment of semiconductor die 104 with alignment notch 130 to die pad 182 can be offset for reliable and repeatable wirebonding.

Bond wire 184 is connected between conductive layer or contact pad 112 on active surface 110 and wire bond pad 186. Die pad 182 and wire bond pad 186 represent a portion of a leadframe, substrate, interposer, or semiconductor die. An encapsulant or molding compound 190 is deposited over semiconductor die 104, bond wire 184, and wire bond pad 186 using a compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, or other suitable applicator. Encapsulant 190 can be polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 190 is non-conductive, provides physical support, and environmentally protects the semiconductor device from external elements and contaminants.

In general, alignment notch 130 can be a one-sided, two-sided, three-sided, or four-sided sidewall structure to partially or completely contain the die pad. Notch 130 provides alignment in mounting semiconductor die 104 to the die pad, as well as stiffness and stability for the semiconductor die. Semiconductor die 104 is robust against laterally slippage, tilting, shifting, or detachment with respect to the die pad because the surfaces of the die pad are disposed at least partially within notch 130. Alignment notch 130 allows for thinner semiconductor die 104 to accommodate the height requirements of the bond wires in a thinner semiconductor package, while avoiding the manufacturing slippage, tilt, rotation, or detachment defect.

FIGS. 7a-7g illustrate another process of forming an alignment notch in back surface 108 of semiconductor die 104 with backside metal within the notch. Continuing from FIG. 2c , a portion of back surface 108 is removed by grinder 200 in a backgrinding operation. The backgrinding operation reduces a thickness of base substrate material 102 and exposes surface 202 of the base substrate material. FIG. 7b shows semiconductor wafer 100 after the backgrinding operation.

In FIG. 7c , semiconductor wafer 100 is inverted and a masking layer 206 is disposed over surface 202 of base substrate material 102. Masking layer 206 can be implemented as a photoresist layer or oxide layer with openings 208 extending to surface 202.

In FIG. 7d , surface 202 is plasma etched through openings 208 in masking layer 206 to form alignment notches or keyed recesses 210 in base substrate material 102 while in wafer form of FIG. 2a . Alternatively, alignment notches or keyed recesses 210 in base substrate material 102 can be formed by LDA or other wet or dry chemical etching process. Alignment notches 210 have side surfaces 212 and back surface 214. Alignment notches 210 make a non-uniform thickness or surface of base substrate material 102.

In FIG. 7e , an electrically conductive layer 216 is formed over masking layer 206 and into alignment notches or keyed recesses 210 using PVD, CVD, electrolytic plating, electroless plating process, or other suitable metal deposition process. Conductive layer 216 includes one or more layers of Al, Cu, Sn, Ni, Au, Ag, Ti, TiW, or other suitable electrically conductive material or combination thereof. Conductive layer 216 operates a backside metal in alignment notches 210 of base substrate material 102 for electrical interconnect or heat dissipation.

In FIG. 7f , masking layer 206 is removed taking along with it the portion of conductive layer 216 formed over the masking layer. Semiconductor die 104 are shown with alignment notches or keyed recesses 210 having side surfaces 212 and back surface 214 in base substrate material 102. Conductive layer 216 remains within alignment notches 210.

In FIG. 7g , semiconductor wafer 100 is disposed over film frame or backing tape 218 with surface 202 and alignment notches 210 oriented toward the film frame. Semiconductor wafer 100 is singulated through saw street 106 into individual semiconductor die 104 using plasma etching. Plasma etching has advantages of removing base substrate material 102 to form precision surfaces, while retaining the structure and integrity of the base substrate material. Alternatively, semiconductor wafer 100 is singulated through saw street 106 using a saw blade or laser cutting tool 220 into individual semiconductor die 104. The individual semiconductor die 104 can be inspected and electrically tested for identification of known good die post singulation. Alternatively, active surface 110 of semiconductor wafer 100 can be oriented toward film frame 218 while the wafer is singulated using any of the aforementioned methods.

FIG. 8 illustrates a semiconductor package 230 containing semiconductor die 104 with alignment notch or keyed recess 210 formed in base substrate material 102 containing back metal conductive layer 216 disposed over die pad 232. In particular, surfaces 212 and 214 of notch 210 provide alignment for mounting semiconductor die 104 to die pad 232. Semiconductor die 104 is larger than die pad 232 resulting in a significant extension of base substrate material 102 beyond the die pad. Die pad 232 is completely contained with alignment notch 210 to securely hold semiconductor die 104 to the die pad. The smaller die pad 232 allows for smaller semiconductor package dimensions and package footprint to meet industry demands. Backside metal conductive layer 216 provides electrical interconnect or heat dissipation. Even with the smaller die pad 232, semiconductor die 104 is robust against laterally slippage, tilting, shifting, or detachment with respect to the die pad because the surfaces of the die pad are disposed within notch 210. Semiconductor die 104 can be significantly larger than die pad 232 with the use of alignment notch 210 containing back metal conductive layer 216, while avoiding the manufacturing slippage, tilt, rotation, or detachment defect noted in FIGS. 1a -1 b.

Bond wire 234 is connected between conductive layer 112 on active surface 110 and wire bond pad 236. Die pad 232 and wire bond pad 236 represent a portion of a leadframe, substrate, interposer, or semiconductor die. An encapsulant or molding compound 240 is deposited over semiconductor die 104, bond wire 234, and wire bond pad 236 using a compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, or other suitable applicator. Encapsulant 240 can be polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 240 is non-conductive, provides physical support, and environmentally protects the semiconductor device from external elements and contaminants.

FIG. 9 illustrates a semiconductor package 250, similar to FIG. 8, containing semiconductor die 104 with a shallow alignment notch or keyed recess 210 formed in base substrate material 102 and containing back metal conductive layer 216 disposed over die pad 252. In particular, surfaces 212 and 214 of notch 210 provide alignment for mounting semiconductor die 104 to die pad 252. Semiconductor die 104 is larger than die pad 252 resulting in a significant extension or overhang of base substrate material 102 beyond the die pad. Die pad 252 is partially contained with alignment notch 210 to securely hold semiconductor die 104 to the die pad. A portion of die pad 252 extends vertically outside notch 210. The smaller die pad 252 allows for smaller semiconductor package dimensions and package footprint to meet industry demands. Backside metal conductive layer 216 provides electrical interconnect or heat dissipation. Even with the smaller die pad 252, semiconductor die 104 is robust against laterally slippage, tilting, shifting, or detachment with respect to the die pad because the surfaces of the die pad are disposed within notch 210. Semiconductor die 104 can be significantly larger than die pad 252 with the use of alignment notch 210, while avoiding the manufacturing slippage, tilt, rotation, or detachment defect noted in FIGS. 1a -1 b.

Bond wire 254 is connected between conductive layer 112 on active surface 110 and wire bond pad 256. Die pad 252 and wire bond pad 256 represent a portion of a leadframe, substrate, interposer, or semiconductor die. An encapsulant or molding compound 260 is deposited over semiconductor die 104, bond wire 254, and wire bond pad 256 using a compressive molding, transfer molding, liquid encapsulant molding, vacuum lamination, or other suitable applicator. Encapsulant 260 can be polymer composite material, such as epoxy resin with filler, epoxy acrylate with filler, or polymer with proper filler. Encapsulant 260 is non-conductive, provides physical support, and environmentally protects the semiconductor device from external elements and contaminants.

FIGS. 10a-10c illustrate semiconductor die with elongated alignment notches formed in the back surface of the die and mounted to mating protrusions formed over a substrate. FIG. 10a is an orthogonal view of semiconductor die 270 including an elongated alignment notch 272 formed in back surface 274 between side surfaces 276 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Likewise, semiconductor die 278 includes an elongated alignment notch 279 formed in back surface 280 between side surfaces 281 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Semiconductor die 270 and 278 can be rectangular, circular, oval, or other geometric shape. Semiconductor die 270 and 278 can be an ASIC, sensor, optical device, detector, VCSEL, waveguide, and multi-chip module. Semiconductor die 270 and 278 are positioned over substrate 282 with alignment protrusions 283. Substrate 282 can be a printed circuit board (PCB), flexible wiring harness, ceramic board, or glass substrate. Substrate 282 can also be a leadframe, interposer, or semiconductor die. Notches 272 and 279 are aligned with substrate protrusions 283.

FIG. 10b is a bottom view of semiconductor die 270 with alignment notch 272 formed in back surface 274 between side surfaces 276 of the semiconductor die, and semiconductor die 278 with alignment notch 279 formed in back surface 280 between side surfaces 281 of the semiconductor die.

In FIG. 10c , semiconductor die 270 and 278 are mounted to substrate 282 with precise alignment as notches 272 and 279 are inserted into substrate protrusions 283. Alignment notches 272 and 279 and substrate protrusions 283 provide a keyed recess for easy placement and precise alignment of semiconductor die 270 and 278 on substrate 282 to lock the semiconductor die in position on the substrate in the y-z directions.

FIGS. 11a-11c illustrate semiconductor die with cross-shaped alignment notches formed in the back surface of the die and mounted to mating cross-shaped protrusions formed over a substrate. FIG. 11a is an orthogonal view of semiconductor die 284 including a cross-shaped alignment notch 285 formed in back surface 286 between side surfaces 287 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Likewise, semiconductor die 288 includes a cross-shaped alignment notch 290 formed in back surface 292 between side surfaces 294 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Semiconductor die 284 and 288 can be rectangular, circular, oval, or other geometric shape. Semiconductor die 284 and 288 can be an ASIC, sensor, optical device, detector, VCSEL, waveguide, and multi-chip module. Semiconductor die 284 and 288 are positioned over substrate 296 with cross-shaped alignment protrusions 298. Substrate 296 can be a PCB, flexible wiring harness, ceramic board, or glass substrate. Substrate 296 can also be a leadframe, interposer, or semiconductor die. Cross-shaped notches 285 and 290 are aligned with cross-shaped substrate protrusions 298.

FIG. 11b is a bottom view of semiconductor die 284 with cross-shaped alignment notch 285 formed in back surface 286 between side surfaces 287 of the semiconductor die, and semiconductor die 288 with cross-shaped alignment notch 290 formed in back surface 292 between side surfaces 294 of the semiconductor die.

In FIG. 11c , semiconductor die 284 and 288 are mounted to substrate 296 with precise alignment as cross-shaped notches 285 and 290 are inserted into cross-shaped substrate protrusions 298. Cross-shaped alignment notches 285 and 290 and cross-shaped substrate protrusions 298 provide a keyed recess for easy placement and precise alignment of semiconductor die 284 and 288 on substrate 296. Cross-shaped notches 285 and 290 inserted into cross-shaped substrate protrusions 298 lock semiconductor die 284 and 288 in position on substrate 296 in x-y-z directions.

FIGS. 12a-12c illustrate semiconductor die with elongated alignment protrusions formed in the back surface of the die and mounted to mating recesses formed in a substrate. FIG. 12a is an orthogonal view of semiconductor die 300 including an elongated alignment protrusion 302 formed over back surface 304 between side surfaces 306 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Likewise, semiconductor die 308 includes an elongated alignment protrusion 309 formed over back surface 310 between side surfaces 311 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Semiconductor die 300 and 308 can be rectangular, circular, oval, or other geometric shape. Semiconductor die 300 and 308 can be an ASIC, sensor, optical device, detector, VCSEL, waveguide, and multi-chip module. Semiconductor die 300 and 308 are positioned over substrate 312 with alignment notches 313. Substrate 282 can be a PCB, flexible wiring harness, ceramic board, or glass substrate. Substrate 312 can also be a leadframe, interposer, or semiconductor die. Protrusions 302 and 309 are aligned with substrate notches 313.

FIG. 12b is a bottom view of semiconductor die 300 with alignment protrusion 302 formed over back surface 304 between side surfaces 306 of the semiconductor die, and semiconductor die 308 with alignment protrusion 309 formed over back surface 310 between side surfaces 311 of the semiconductor die.

In FIG. 12c , semiconductor die 300 and 308 are mounted to substrate 312 with precise alignment as protrusions 302 and 309 insert into substrate notches 313. Alignment protrusions 302 and 309 formed in back surfaces 304 and 310 of semiconductor die 300 and 308 provide a keyed recess for easy placement and precise alignment of the semiconductor die on substrate 312 to lock the semiconductor die in position on the substrate in the y-z directions.

FIGS. 13a-13c illustrate semiconductor die with cross-shaped alignment protrusions formed in the back surface of the die and mounted to mating cross-shaped recesses formed in a substrate. FIG. 13a is an orthogonal view of semiconductor die 314 including cross-shaped alignment protrusion 315 formed over back surface 316 between side surfaces 317 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Likewise, semiconductor die 318 includes cross-shaped alignment protrusion 320 formed over back surface 322 between side surfaces 324 of the semiconductor die using plasma etching, wet etching, milling, laser, or dry etching. Semiconductor die 314 and 318 can be rectangular, circular, oval, or other geometric shape. Semiconductor die 314 and 318 can be an ASIC, sensor, optical device, detector, VCSEL, waveguide, and multi-chip module. Semiconductor die 314 and 318 are positioned over substrate 326 with cross-shaped alignment notches 328. Substrate 326 can be a PCB, flexible wiring harness, ceramic board, or glass substrate. Substrate 326 can also be a leadframe, interposer, or semiconductor die. Cross-shaped protrusions 315 and 320 are aligned with cross-shaped substrate notches 328.

FIG. 13b is a bottom view of semiconductor die 314 with cross-shaped alignment protrusion 315 formed over back surface 316 between side surfaces 317 of the semiconductor die, and semiconductor die 318 with cross-shaped alignment protrusion 320 formed over back surface 322 between side surfaces 324 of the semiconductor die.

In FIG. 13c , semiconductor die 314 and 318 are mounted to substrate 326 with precise alignment as cross-shaped protrusions 315 and 320 insert into cross-shaped substrate notches 328. Cross-shaped alignment protrusions 315 and 320 and cross-shaped substrate notches 328 provide a keyed recess for easy placement and precise alignment of semiconductor die 314 and 318 on substrate 326. Cross-shaped protrusions 315 and 320 inserted into cross-shaped substrate notches 328 lock semiconductor die 314 and 318 in position on substrate 326 in x-y-z directions.

FIGS. 14a-14b illustrate semiconductor die with alignment recesses (or protrusions) formed in the back surface of the die and mounted to mating structures formed in a PCB. In FIG. 14a , semiconductor die 330 and 332 are positioned over PCB 340 with corresponding alignment protrusions (or recesses) 342 and 344 formed by plasma etching, wet etching, milling, laser, or dry etching. Recesses 346 and 348 in semiconductor die 330 and 332 are also formed by plasma etching, wet etching, milling, laser, or dry etching. Recess 346 in semiconductor die 330 is aligned with PCB protrusion 342, and recess 348 in semiconductor die 332 is aligned with PCB protrusion 344. In FIG. 14b , semiconductor die 330 and 332 are mounted to PCB 340 with precise alignment as recesses 346 and 348 are inserted into the PCB protrusions 342 and 344, respectively. Alignment recesses 346 and 348 formed in the back surfaces of semiconductor die 330 and 332 provide a keyed recess for easy placement and precise alignment of the semiconductor die on PCB 340.

FIGS. 15a-15c illustrate semiconductor die 350 a-350 b with alignment protrusions 352 formed in back surface 354 of the die using plasma etching, wet etching, milling, laser, or dry etching and inserted into mating openings 358 formed through substrate 360. FIG. 15a shows semiconductor die 350 a-350 b positioned over substrate 360 with alignment protrusions 352 aligned with openings 358. Substrate 360 can be a PCB, flexible wiring harness, ceramic board, or glass substrate. Substrate 360 can also be a leadframe, interposer, or semiconductor die. FIG. 15b is a bottom view of semiconductor die 350 a-350 b with alignment protrusions 352 formed over back surface 354.

In FIG. 15c , semiconductor die 350 a-350 b are mounted to substrate 360 with alignment protrusions 352 extending through openings 358. Alignment protrusions 352 and openings 358 provide a keyed mating structure for easy placement and precise alignment of semiconductor die 350 a-350 b on substrate 360. Fasteners 362 are attached to protrusions 352 on the back side of substrate 360 opposite semiconductor die 350. Fasteners 362 securely hold semiconductor die 350 a-350 b to substrate 360. The alignment arrangement in FIGS. 15a-15c allows semiconductor die 350 a-350 b to positioned on substrate 360 so that side surface 364 of semiconductor die 350 a is in direct physical contact with side surface 364 of semiconductor die 350 b. Fasteners 362 eliminate the need for die attach adhesive so no material will occupy the space between semiconductor die 350 a-350 b. Alternatively, alignment protrusions 352 extend into openings 358 partially through substrate 360. An electrical connection is made to alignment protrusions 352 for fastening in place structurally, thermal, and/or for electrical connection.

While one or more embodiments have been illustrated and described in detail, the skilled artisan will appreciate that modifications and adaptations to those embodiments may be made without departing from the scope of the present disclosure. 

What is claimed:
 1. A method of making a semiconductor device, comprising: providing a semiconductor die including a base material; and removing a portion of the base material to form an alignment recess or alignment protrusion in a surface of the base material.
 2. The method of claim 1, further including: providing a substrate; and disposing the semiconductor die over the substrate with a portion of the substrate within the alignment recess.
 3. The method of claim 2, wherein the substrate includes a leadframe, interposer, or semiconductor die.
 4. The method of claim 2, wherein the portion of the substrate is disposed partially within the alignment recess of the base material.
 5. The method of claim 1, further including utilizing plasma etching to remove the portion of the base material.
 6. The method of claim 1, wherein the alignment recess extends a length of the base material.
 7. A semiconductor device, comprising: a semiconductor die including a base material; and an alignment recess or alignment protrusion formed in a surface of the base material.
 8. The semiconductor device of claim 7, further including a substrate, wherein the semiconductor die is disposed over the substrate with a portion of the substrate within the alignment recess.
 9. The semiconductor device of claim 8, wherein the portion of the substrate includes a die pad.
 10. The semiconductor device of claim 8, wherein the portion of the substrate is disposed partially within the alignment recess of the base material.
 11. The semiconductor device of claim 7, further including a substrate, wherein the semiconductor die is disposed over a substrate with a portion of the alignment protrusion within a recess of the substrate.
 12. The semiconductor device of claim 7, wherein the alignment recess or alignment protrusion extends a length of the base material.
 13. The semiconductor device of claim 7, further including a metal layer formed in the alignment recess of the base material.
 14. A semiconductor device, comprising a semiconductor die including a base material comprising a first surface and a non-uniform second surface for alignment.
 15. The semiconductor device of claim 14, wherein the non-uniform second surface includes an alignment recess or alignment protrusion.
 16. The semiconductor device of claim 15, further including a substrate, wherein the semiconductor die is disposed over the substrate with a portion of the substrate within the alignment recess.
 17. The semiconductor device of claim 16, wherein the portion of the substrate includes a die pad.
 18. The semiconductor device of claim 16, wherein the portion of the substrate is disposed partially within the alignment recess of the base material.
 19. The semiconductor device of claim 15, further including a metal layer formed in the alignment recess of the base material.
 20. The semiconductor device of claim 15, further including a substrate, wherein the semiconductor die is disposed over a substrate with a portion of the alignment protrusion within a recess of the substrate. 